Drum tuning mechanism



Jan. 3, 1956 w. F. LUDWIG 2,729,133

DRUM TUNING MECHANISM Filed Sept. 9, 1954 2 Sheets-Sheet 1 Jan. 3, 1956 w. F. LUDWIG 2,729,133

DRUM TUNING MECHANISM FiledSept. 9, 1954 2 Sheets-Sheet 2 IN V EN TOR.

specification and inv which like United States Patent DRUM TUNING MECHANISM William F. Ludwig, Chicago, Ill. Application September 9, 1954, Serial No. 454,989 3 Claims. (Cl. 84-419) This invention relates to drums and tuning mechanisms therefor. More particularly, it is concerned with a tuning device for tympani though the principle may be applied to other types of drums.

Tympani or kettle drums are used in pairs and it is necessary to vary the tuning thereof at frequent intervals. Accordingly, rapid and easy tuning is an allimportant feature in efiicient tympani.

In the standard size tympani, the large kettle is 28 inches in diameter and the small kettle is 25 inches in diameter, there being one octave between the two. Each has a range of five tones. On the smaller kettle the tension increases from a pull of 80' pounds to a pull of 1500 pounds when tuning from the lowest natural note B to the high note F.

The problem of providing a mechanism which will tune from one extreme to the other with a minimum of effort has been before the industry for many years and numerous solutions have been suggested. There are in existence many types of foot pedal mechanisms for tuning tympani but the present invention relates to hand-tuned tympani, the area in which the tuning problem has been most acute.

In the interest of speed and uniformity, it is, of course, necessary to accomplish the tuning by adjusting a single instrumentality, and all the known devices of this type are onlysatisfactory when tuning low notes but become diflicult to adjust when the high notes are reached.

It is the principal object of the present invention to provide a drum-tuning device having a single, fast-acting, hand-controlled mechanism that provides any increased mechanical advantage as the tuning tension increases; that is reliable, simple, and positive in operation; that is compactly arranged internally of a housing; that is economical to produce; and that may be easily packed for transportation.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings forming a part of this numerals are employed to designate like parts throughout the same:

Fig. 1 is a sectional elevational view of a drum in accordance with the present invention;

2 s n un rneath view of the drum of Fig. 1;

Fig. 3 is a detailed sectional view of the leverage mechanism of the present invention;

Figs. 4, 5, and 6 are detailed perspective views of cerrain of the levers of the leverage mechanism; and

Fig. 7 is a detailed sectional view of the hand-operated screw mechanism.

It should be understood that the description of the preferred form of the invention is for the purpose of complying with section 112, title 35 of the United States Code, and that the appended claims should be construed as broadly as the prior art will permit.

Briefly the present invention is concerned with a handoperated single screw adjusting mechanism that is mounted on a conventional tympanum. In the preferred eminvention.

bodiment a leverage system is mounted within a housing that is secured to the bottom of the kettle and this leverage system provides an increasing mechanical advantage as the tension on the drum head increases. The operating mechanism and leverage system are preferably used in conjunction with the conventional peripheral adjusting screws and cooperating bell cranks that serve to initially tune the drum head.

Referring now to the drawings, there is illustrated a substantially hemispherical kettle 10 that may be made of copper, alumium, or any other suitable material. A drum head 12 is held in an annular hoop 14 that telescopes over the top of the kettle. The hoop 14 is provided with a series of equally spaced bosses 16 around its outer periphery and these bosses receive, in threaded engagement, a series of adjusting screws 18. The screws 18 cooperate with bell cranks 20 that are attached to the side of the drum by means of brackets 22. At their lower ends the bell cranks 20 are attached to a series of radial tension rods 24 which are actuated by the mechanism of the present invention. The arrangement of the hoop 14, adjusting screws 18, bell cranks 20, and radial tension rods 24 is. old and forms no part of the present The radial tension rods are received in sockets provided in a spider 26 which is secured to an axial tension rod 28 by means of a pair of nuts 30. The other end of the rod 28 is threadedly received in an axially tapped hole provided in a connecting link 32. The connecting link 32 is pivotally secured to the leverage mechanism of the present invention.

As best seen in Figs. 2 and 3, the leverage mechanism is mounted in a housing 34 formed integrally with a base plate 36, the base plate 36 being secured to the bottom of the kettle 10. The housing 34 extends from the center of the base plate 36 outwardly a suificient distance to receive the lower end of the operating mechanism designated generally at 38. The leverage mechanism consists of a pair of hell cranks 40 and 42 pivotally mounted in the housing 34 on a pair of trunnion pins 41 and 43 respectively. The bell cranks are arranged in a common plane and a connecting linkage, comprising a pair of levers 44 and 46 respectively, and a threaded rod 48 joining the two, pivotally engages the bell cranks.

The inner bell crank 42, as shown in Fig. 5, is of a generally triangular shape and is provided with bosses at each of the corners. The boss 50 which receives the trunnion pin 43 is somewhat larger than the others. The lower end of the connecting link 32 is bifurcated and straddles the boss 52'. These parts are pivotally connected by a pin 54. The lever 46 is also bifurcated to straddle the boss 56 and is pivoted thereto by a pin 58.

it should be noted that the bell crank 42 is arranged so that as the axial tension rod 28 is pulled downwardly, the efiective leverage between bosses 50 and 56 increases. In other words, as: the. tension on the axial rod 28 increases, the mechanical advantage provided by the bell crank 42' also. increases and compensates for the increased tension. In this manner the tension on the connecting linkage 44, 46, and 48 increases at a slower rate than does the tension on the rod 28.

The bell crank 40, as shown in detail in Fig. 6, also has a large boss 58 which receives the trunnion pin 41. The longer arm 60 of this bell crank is provided with a boss 62 and the shorter arm is provided with a boss 64. The lever 44 is bifurcated to straddle the boss 64 and is held in pivotal engagement therewith by a pin 66.

The operating mechanism 38 is connected to the longer arm 60 of the bell crank 40 by a bifurcated lever 68, the arms 69 of which straddle the boss 62 and are pivotally secured thereto by a pin 70.

The arrangement of the bell crank 40 is another important feature of the present invention. Referring again to Fig. 3, in which the line 72 indicates the path of travel of thepin '70 and the line 74 indicates a line drawn through the center line of the pin 41 perpendicular to the path of travel of the lever 68, it may be seen that as the bell crank 44) pivots clockwise about the pin 41, the effective leverage of the arm increases as the line 74 is approached. Ideally, this point corresponds to the maximum range to which it is desired to tune since the effective leverage begins to decrease once this point is passed. Thus the outer bell crank 40 is arranged to also provide an increasing mechanical advantage as the applied tension increases.

According to, the present invention, the bell cranks 40 and 42, each of which provides an increasing mechanical advantage as the tension increases, are coordinated so that the tension in the lever 68 remains substantially constant as the drum is tuned from the low notes to the high notes. Therefore, the tuning effort is unchanged over the entire range.

As shown in Figs. 1 and 7, the operating mechanism is secured to the drum 10 adjacent the top of the drum. This arrangement is sturdy but more important it facilitates tuning in that the operating mechanism is readily accessible. tuning knob 76 removably mounted on a shaft 78 which is threadedly engaged with the lever 68. A bracket 80 is secured to the side of the drum 10 by a pair of screws 82. The bracket 80 is apertured to receive the neck portion 84 of a cup-shaped lower race 85 of an end truss ball-bearing assembly. A plurality of balls 88 ride in the lower race and freely support an upper race 90 that is pinned to the shaft 78, as at 92. This end truss ballbearing assembly permits the shaft to turn in its bearing support with a minimum of resistance.

At the bottom end, the shaft 78 is provided with a screw thread 94 that cooperates with a tapped hole 96 formed at the top of the bifurcated lever 63. The shaft 78 and lever 68 extend into an opening 98 provided in the housing 34 and the adjacent side edges of the housing guide the movement of the lever 68.

. The operation of the leverage system is simple and efficient. When it is desired to increase tension, the knob 76 is turned so as to cause the lower end of the shaft 78 to draw the lever 68 upwardly. This pivots the bell cranks 40 and 42 clockwise, as viewed in Figs. 1 and 3, and draws the axial tension rod downwardly. Since the spider 26 is rigidly mounted on the rod 28, it will move downwardly and exert increased tension on the radial tension rods 24. The rods 24 pivot the bell cranks 20 to pull the hoop 14 and drum head 12 tightly down onto the kettle 10.

During the above operations, the bell cranks 40 and 42 are each approaching a condition of right angle leverage and thus each provides an increasing mechanical advan tage as the tension is increased. This arrangement per- .mits the shaft 78 to maintain substantially constant tension though the tension applied to the drum head varies over a wide range.

Another important feature of the tympanum of the present invention is the ease with which it may be transported. The supporting legs 100 are telescoped within The operating mechanism consists of a bosses 102 provided on the base plate. A set screw 104 passes through each ofthebosses and is adapted to engage the legs 100 to provide an adequate support for the tympanurn. In packing the tympanum, the pressure of the screws 104 is merely relieved to permit the legs 100 to retract into the kettle 10. They are held in this out-ofthe-way position by again tightening the screws.

In regard to packing the tympanum, it should be noted that the handle knob 76 is readily removable from the shaft 78. To facilitate this, the upper end of the shaft is formed with a plurality of fiat faces 108 that are tapered in the direction of the upper end of the shaft. The recess 110 in the knob is provided with a plurality of mating fiat faces so that when the knob is positioned on the shaft, the cooperating faces engage each other. With this arrangement the knob is freely removable but when in position engages the shaft to turn the same.

I claim:

1. In a drum including a casing supported in spaced relationship above a floor by a plurality of legs and having a central axis, and a drum head disposed perpendicularly to said axis, the combination with drum-head tensioning mechanism, including bell crank levers and adjusting devices engaged with the latter and the drumhead hoop, of radial tension rods connecting the bell crank levers with an axial tension rod disposed centrally of the drum casing and extending transversely of the drum head, said axial tension rod passing through an opening at the bottom of the drum, a housing including a mounting plate secured to the bottom of the easing for supporting said housing in spaced relationship above the floor, a leverage system mounted in the housing and comprising a pair of aligned bell cranks spaced from each other and connected by a link, one of the bell cranks of said leverage system being connected to said axial tension rod, and an operating mechanism having a single hand screw mounted on the casing adjacent the drum head, said screw being operatively connected to the other bell crank of said leverage system to move said axial tension rod toward and away from said drum head and cause said radial tension rods to expand and contract to actuate said first-named bell crank levers to apply equal tension on the drum head, the bell cranks of the leverage system being arranged to provide an increased mechanical advantage as the tension increases.

2. The arrangement claimed in claim 1, wherein the single hand screw is rotatably supported on the casing adjacent the drum head and actuates said operating mechanism through an intermediate member that is in threaded relationship with said screw and that is pivoted on said other bell crank.

3. The arrangement claimed in claim 1, wherein the single hand screw passes through a guide slot formed in a plate projecting laterally from said housing, said slot being aligned with the bell cranks of said leverage system.

References Cited in the file of this patent UNITED STATES PATENTS 

